Related Rule
South Africa
Practice Relating to Rule 77. Expanding Bullets
South Africa’s LOAC Manual (1996) provides: “Weapons which are calculated to cause unnecessary suffering are illegal per se. Such weapons include … dum-dum bullets.” 
South Africa, Presentation on the South African Approach to International Humanitarian Law, Appendix A, Chapter 4: International Humanitarian Law (The Law of Armed Conflict), National Defence Force, 1996, § 34(f)(i).
South Africa’s Revised Civic Education Manual (2004) states:
i. Prohibited Weapons. The following weapons have been prohibited:
(2) Expanding Bullets. The Hague Declaration outlawing them in 1899. 
South Africa, Revised Civic Education Manual, South African National Defence Force, 2004, Chapter 4, § 56(f)(i).
South Africa’s ICC Act (2002) reproduces the war crimes listed in the 1998 ICC Statute, including “employing bullets which expand or flatten easily in the human body” in international armed conflicts. 
South Africa, ICC Act, 2002, Schedule 1, Part 3, § (b)(xix).